# Measuring the speed of light with chocolate chips

Matthew writes – “As any decent cook knows, microwaves do not heat evenly. In fact, this article explains that their heating patterns are relative to the speed of light! You can even measure the uneven heating of chocolate chips and solve for the speed of light.”Link.

## 6 thoughts on “Measuring the speed of light with chocolate chips”

1. Bugmenot says:

This is just stupid. You’re relying on the stated frequecy of the microwave. This frequency is basically computed by doing exactly the same experiment and taking the known speed of light to calculate the frequency of the microwave.

It’s like me looking at the speedometer, subtracting 30 from the speed and telling you that number. Then you “measure” the speed without a speedometer by adding 30 to the number I gave you.

2. Johthe says:

I’m sure the people who make the microwave use a bit more precise method to calculate frequency, such as knowing exactly how their machine works and calculating it from how they made it – not measuring wavelength with chocolate chips – or anything else for that matter. Cool project/idea I’d say!

3. pelrun says:

Bugmenot is quite wrong – the entire design of the microwave starts with the frequency used. It’s fixed, because they have to use the frequencies that water will absorb.

Which is 2.4GHz to 2.5GHz.

Yes, the same range 802.11b wireless, bluetooth, and all those AV sender units use. There’s a reason the government let people use that band without requiring a license… because they thought it was mostly worthless anyway due to the water issue. The design engineers just saw it as a challenge and got clever instead.

Anyway, since the microwave must operate in the water-absorption band, the design of the magnetron (which generates the microwaves) and the rest of the microwave is all calculated from that one figure. Knowing it and how far the hotspots are apart lets you solve for the speed of light.

What, you thought that “make hotspots 6cm apart” was the key to how a microwave worked? Hahahahaha. The hotspots are an artifact, not a design decision – why do you think microwaves generally have rotating turntables?

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